Diarylpentanoids from Diplomorpha canescens and Diplomorpha ganpi

Two new α-hydroxy ketone type diarylpentanoids, diplomorphanone A, 2(S)-hydroxy-1-(4-hydroxyphenyl)-5-phenyl-1-pentanone (1) and diplomorphanone B, 2(R)-hydroxy-1,5-diphenyl-1-pentanone (2) were isolated from aerial parts of Diplomorpha canescens (Meisn.) C.A. Meyer and roots of Diplomorpha ganpi (Sieb. et Zucc.) Nakai, respectively. Nine known compounds including diarylpentanoids (3–6), phenylpropanoid derivatives (7–9), (+)-afzelechin (10) and apiosylskimmin (11) were also isolated for the first time from D. ganpi. Structures of these compounds were elucidated on the basis of spectroscopic data.     

Caged xanthones displaying protein tyrosine phosphatase 1B (PTP1B) inhibition from Cratoxylum cochinchinense

Four new caged xanthones (1–4) and two known compounds (5, 6) were isolated from the roots of Cratoxylum cochinchinense, a polyphenol rich plant, collected in China. The structures of the isolated compounds (1–6) were characterized by obtaining their detailed spectroscopic data. In particular, compounds 1 and 6 were fully identified by X-ray crystallographic data. The isolated compounds (1–6) were evaluated against protein tyrosine phosphatase 1B (PTP1B), which plays an important role in diabetes, obesity, and cancer. Among these compounds, 3, 4, and 6 displayed significant inhibition with IC₅₀ values of 76.3, 43.2, and 6.6 µM, respectively. A detailed kinetic study was conducted by determining K_m, V_max, and the ratio of K_ik and K_iv, which revealed that all the compounds behaved as competitive inhibitors.     

Three new phthalide glycosides from the rhizomes of Ligusticum chuanxiong

Three new phthalide glycosides, named chuanxiongoside A (1), chuanxiongoside B (2) and ligusticoside B (3) together with two known glycosides, celephthalide A (4) and icariside F₂ (5), were isolated from the rhizomes of Ligusticum chuanxiong. This is the first report of compounds 4⿿5 from the title plant. The structures of compounds 1⿿3 were identified using various spectroscopic methods.     

Anti-HBV active constituents from Piper longum

In the screening search for Hepatitis B virus inhibitory agents from medicinal plants, the ethanol extract of Piper longum Linn. was found to possess superior anti-HBV activity in vitro. Bioassay-guided fractionation coupled with repeated purification resulted in the isolation of four new compounds, involving two new glycosides longumosides A (1) and B (2) and two new amide alkaloids erythro-1-[1-oxo-9(3,4-methylenedioxyphenyl)-8,9-dihydroxy-2E-nonenyl]-piperidine (3), threo-1-[1-oxo-9(3,4-methylenedioxyphenyl)-8,9-dihydroxy-2E-nonenyl]-piperidine (4), as well as two compounds 3β,4α-dihydroxy-2-piperidinone (5), 5,6-dihydro-2(1H)-pyridinone (6) from natural source for the first time. The structures of the four new compounds were determined by extensive analyses of the MS, IR, 1D and 2D NMR data. Besides, the compounds 2–6, together with the known compounds 7–11 obtained previously, were assayed for their anti-HBV activity by using Hep G 2.2.15 cell line in vitro. Results suggested the compound piperine (7) possessed remarkable inhibitory HBV activity, against the secretion of hepatitis B virus surface antigen (HBsAg) and hepatitis B virus e antigen (HBeAg) with the Selectivity Index (SI) values of 15.7 and 16.8, respectively.     

Two novel saponins from Cephalaria davisiana (Dipsacaceae)

Two novel hederagenin type triterpene saponins, namely davisianoside A (1) and davisianoside B (2) together with ten known compounds (3–12) were isolated from the aerial parts of Cephalaria davisiana (Dipsacaceae). One new prosapogenin (1a) was also obtained after the alkaline hydrolysis of compound 1. The chemical structures of all compounds were established mainly by 1D-, 2D-NMR and HR-ESI/MS analysis as well as chemical methods.The antibacterial and antifungal effects of compounds 1–2 were evaluated against Gram-positive, Gram-negative bacteria and unicellular yeast C. albicans by MIC method.     

Isopimarane diterpenes and flavan derivatives from the twigs of Caesalpinia furfuracea

The first phytochemical investigation of Caesalpinia furfuracea twigs led to the isolation and identification of four new compounds including two isopimarane diterpenes, caesalfurfuric acids A (1) and B (2), and two flavans, (2R)-caesalflavans A (5) and B (6), together with four known compounds, 4-epi-isopimaric acid (3), methyl (E)-3-(3,4-dihydroxyphenyl)acrylate (4), (E)-resveratrol (7) and oxyresveratrol (8). Their structures were elucidated by intensive spectroscopic analysis. Compound 1 was found to exhibit antibacterial activity against MRSA SK1 with an MIC value of 16 μg/mL.     

Neo-clerodane diterpenes from Ajuga turkestanica

The ethyl acetate extract of the aerial parts of Ajuga turkestanica afforded 6 neo-clerodane diterpenes, including two novel compounds, 14,15-dihydroajugachin B (1) and 14-hydro-15-methoxyajugachin B (2), in addition to the known diterpenoids chamaepitin (3), ajugachin B (4), ajugapitin (5) and lupulin A (6). Structures were established through exhaustive NMR spectroscopic analysis and chemical transformation in the case of 1. The full ¹H and ¹³C NMR assignment of the C-15 R and S configurations of 14-hydro-15-methoxyajugachin B and chamaepitin were elucidated.     

Cytotoxic xanthene derivatives from Homalium paniculiflorum

Two new xanthene derivatives, homapanicones A (1) and B (2), along with 11 known compounds (3–13), were isolated from the stems of Homalium paniculiflorum. Among them, homapanicones A (1) and B (2) represent the first example of naturally occurring xanthene derivatives with an oxidized aromatic B unit, and the known compounds (3–13) were isolated from this plant for the first time. These structures were established on the basis of extensive spectroscopic methods. Compounds 1 and 2 were tested for their cytotoxicities on HL-60, SMMC-7721, A-549, MCF-7, and SW480 human tumor cell lines. Homapanicones A (1) and B (2) showed cytotoxicities against various human cancer cell lines in the range of IC₅₀ at 4.08–24.14 μM.     

A pair of new tetrahydro-naphthalenone enantiomers from Eremurus altaicus (Pall.) Stev.

A new racemic mixture of a 4-hydroxytetralone derivative, altaicusin A (1), was isolated from the whole plant of Eremurus altaicus (Pall.) Stev., together with three anthraquinones (compounds 2–4) and two naphthalene derivatives (5–6). The racemic altaicusin A (1) was further purified by chiral HPLC to yield a pair of enantiomers, (+)-(4S)-altaicusin A (1a) and (−)-(4R)-altaicusin A (1b). Their structures were established on the basis of spectroscopic analysis, including IR, HR-TOF-MS, and NMR. The absolute configurations of compounds 1a and 1b were elucidated by quantum chemical ECD calculations. Compounds 3 and 6 exhibited inhibitory activity against protein tyrosine phosphatase 1B (PTP1B).     

N-containing compounds from Hymenocallis littoralis and their cytotoxicity against Hep3B cells

A chemical study focusing on the N-containing constituents of Hymenocallis littoralis was carried out, leading to the isolation of two new alkaloidal flavonoids (1–2) and five known alkaloids (3-7). Structures of the isolated compounds were established mainly by spectroscopic techniques, including NMR spectroscopy and mass spectrometry as well as the CD experiment. These compounds were subjected to the in vitro cytotoxicity assays using Hep3B cells, and among them only the known pancratistatine (3) and lycorine (5) could significantly inhibit the Hep3B cell proliferation.     

Limonoids from the leaves of Toona ciliata var. yunnanensis

Twelve limonoids, toonayunnanins A–L (1–12) and eleven known compounds (13–23) were isolated from the leaves of Toona ciliata var. yunnanensis, and their structures were elucidated by means of extensive spectroscopic analyses, particularly 1D and 2D NMR techniques. The inhibitory effects of all the isolated compounds were evaluated on human tumor cell lines, such as HL-60, SMMC-7721, A-549, MCF-7 and SW480. Cedrelone (13) and dysobinin (18) showed significant cytotoxicity, and toonayunnanin B (2) and epoxyazadiradione (14), were found to be slightly cytotoxic against the above cell lines. Furthermore, this study provides valuable information for the chemotaxonomy of T. ciliata varieties.     

Chemical constituents from Cistanche sinensis (Orobanchaceae)

Phytochemical investigation of 70% aqueous EtOH extract of Cistanche sinensis led to the isolation of fifteen compounds (1–15), including nine phenylethanoid glycosides (PhGs, 1–9), five iridoid glycosides (10–14), and one lignan glycoside (15). Their structures were determined on the basis of 1D- and 2D-NMR experiments and by comparison with physical data of known compounds. Among the isolated compounds, 1 was identified as a new compound, three compounds (9, 14, and 15) were firstly reported from the genus Cistanche, and seven compounds (2–6, 11, and 12) were isolated from C. sinensis for the first time. PhGs with a 6′-O-rhamnosyl moiety such as cistansinenside B (1), poliumoside (7), and 2′-O-acetylpoliumoside (9) could serve as chemotaxonomic markers to differentiate C. sinensis from other species of Cistanche.     

Minor phenolics from Angelica keiskei and their proliferative effects on Hep3B cells

A new coumarin, (?)-cis-(3′R,4′R)-4′-O-angeloylkhellactone-3′-O-β-d-glucopyranoside (1) and two new chalcones, 3′-[(2E)-5-carboxy-3-methyl-2-pentenyl]-4,2′,4′-trihydroxychalcone (4) and (±)-4,2′,4′-trihydroxy-3′-{2-hydroxy-2-[tetrahydro-2-methyl-5-(1-methylethenyl)-2-furanyl]ethyl}chalcone (5) were isolated from the aerial parts of Angelica keiskei (Umbelliferae), together with six known compounds: (R)-O-isobutyroyllomatin (2), 3′-O-methylvaginol (3), (?)-jejuchalcone F (6), isoliquiritigenin (7), davidigenin (8), and (±)-liquiritigenin (9). The structures of the new compounds were determined by interpretation of their spectroscopic data including 1D and 2D NMR data. All known compounds (2, 3, and 6–9) were isolated as constituents of A. keiskei for the first time. To identify novel hepatocyte proliferation inducer for liver regeneration, 1–9 were evaluated for their cell proliferative effects using a Hep3B human hepatoma cell line. All isolates exhibited cell proliferative effects compared to untreated control (DMSO). Cytoprotective effects against oxidative stress induced by glucose oxidase were also examined on Hep3B cells and mouse fibroblast NIH3T3 cells and all compounds showed significant dose-dependent protection against oxidative stress.     

Further chemical constituents from Sinningia canescens and S. leucotricha (Gesneriaceae)

Four new compounds were isolated from the tubers of Sinningia canescens and S. leucotricha: one naphthoquinone, 7-methoxy-8-hydroxy-α-dunnione (1); two arylbenzofurans, sinningial A (2) and B (3); and one sesquiterpene, 11-epi-subergorgiol (4). Seventeen additional known compounds were isolated and identified. The structures of all compounds were determined by spectroscopic and MS analysis.     

Topoisomerase II inhibitors from the roots of Stellera chamaejasme L.

Three new compounds, including one daphnane diterpene (1), one sesquiterpene (6), and one lignan (7) have been isolated from the Stellera chamaejasme L., together with five other known compounds, including four daphnane diterpenenoids (2–5) and one lignan (8). The structures of the new compounds were elucidated by spectroscopic analysis. The cytotoxicities of compounds 1–8 towards human lung adenocarcinoma cells (A549 cells) were evaluated using a sulforhodamine B assay. All of the compounds displayed significant cytotoxicity, with IC₅₀ values in the ranging of 0.2 nM to 2.0 μM. Mechanistic studies revealed that the antitumor activities of compounds 1–3 and 7 were derived from their inhibition of topoisomerase II (Topo II). Furthermore, as a Topo II inhibitor, compound 1 was found to effectively induced G2-M phase cell cycle arrest and apoptosis in cancer cells.     

Two new phenolic compounds from the white flower of Impatiens balsamina

During the course of our continuing search for biologically active compounds from Korean medicinal sources, we investigated the white flower of Impatiens balsamina. From the MeOH extract, two new phenolic compounds (1–2) containing a nitrile group and eleven known phenolic compounds (3–13) were isolated. The chemical structures of new compounds (1–2) were determined through NMR, HRMS, and CD data. We tested the isolated compounds (1–13) for their cytotoxic activities by determining their inhibitory effects on human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15) in vitro using the sulforhodamine B (SRB) assay. We also investigated their neuroprotective activity by determining their effects on nerve growth factor (NGF) secretion in C6 cells, and anti-neuroinflammatory activity by measuring nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated BV-2 cells.     

New polyoxygenated cyclohexenes isolated from Uvaria rufa and cinnamtannin B1 isolated from Nephelium hypoleucum with TRAIL-resistance-overcoming activity

Bioactivity-guided isolation of Uvaria rufa leaves and Nephelium hypoleucum bark resulted in the successful isolation of nine compounds (1–9) bearing a new polyoxygenated cyclohexene scaffold: zeylenol-6-shikimate (1), (−)-zeylenol (2), microcarpin A (3), uvarigranol F (4), quercetin (5), kaempferol (6), and p-coumaric acid (7) from U. rufa, and epicatechin (8) and cinnamtannin B1 (9) from N. hypoleucum. The structures of the isolated compounds were elucidated using various spectroscopic techniques. All compounds, except for 7, exhibited weak-to-strong TRAIL-resistance-overcoming activity and an increased gastric cancer cell line (AGS) inhibition by 17–32% as compared to the treatment with the compounds alone. Compounds 3 and 9 were studied for their ability to overcome TRAIL resistance using western blot analysis, which indicated that they sensitised AGS cells to apoptosis via both extrinsic and intrinsic pathways by increasing the expression of several proapoptotic proteins (cleaved caspase-3, −8, and −9) and by decreasing the expression of anti-apoptotic protein Bcl-2.     

Sesquiterpenoids and steroids from gorgonian Echinogorgia sassapo reticulate

Three guaiane-type sesquiterpenoids (1−3) and five steroids with 3β-hydroxy-5-en-7-one moiety (4−8) were obtained from gorgonian Echinogorgia sassapo reticulata collected from the South China Sea. Among them, new compound 1 was identified as (1S,5S,8S)-8-methoxy-menelloide B by spectroscopic methods including IR, HRESIMS, 1D and 2D NMR, and ECD spectra. All compounds except for 3 were obtained for the first time from the genus Echinogorgia. The chemotaxonomic significance of these compounds was summarized.     

Chemical constituents from Oncocalyx glabratus and their biological activities

Chemical investigation of the aerial parts of Oncocalyx glabratus resulted in the isolation of three new flavan derivatives, 5,3′,4′-trihydroxyflavan 7-O-gallate (1), 5,4′-dihydroxyflavan 7-3′-O-digallate (2) and 5,3′-dihydroxyflavan 7-4′-O-digallate (3), named oncoglabrinol A, B and C, respectively, together with four known flavonols, (+)-catechin (4), (+)-catechin-7-O-gallate (5), catechin-7-4′-O-digallate (6A) and catechin-7-3′-O-digallate (6B). The structures of the compounds were established by 1D, 2D NMR and ESI-HRMS spectral analyses. The biological activity of the compounds was tested through a series of in vitro assays designed for determining cytotoxicity, antiviral activity against hepatitis B virus, and antidiabetic activity. All compounds were found non-toxic and showed moderate anti-HBV activity. Compounds 3 and 6 showed dual PPAR agonistic activity while others were not effective.     

Four new iridoid glucoside p-coumaroyl esters from Ajuga decumbens

From the methanolic extract of the dried whole plant ofAjuga decumbens, four new iridoid glucosidecis- andtrans-p-coumaroyl esters, decumbeside A (1), B (2), C (7) and D (8) were isolated together with the known reptoside (6) and 8-acetylharpagide (9). The structures of the new compounds have been elucidated on the basis of spectroscopic and chemical evidence.